Attractive well of He–He from 3He–4He differential elastic scattering measurements

Burgmans, A.L.J.; Farrar, James M.; Lee, Y. T.

doi:10.1063/1.432401

Cited by 102 publications

(12 citation statements)

References 31 publications

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“…This minimum is in a very good agreement with the experimental well depth [25], since the remaining 10% of the dispersion energy which could be obtained by extending the basis with higher functions, e.g., 4/, is almost canceled by the effect of intramonomer correlations on the interaction energy. (Such a cancella tion will always occur to some extent since experience teaches that the monomer correlation tends to weaken the dispersion interactions.)…”

Section: Introductionsupporting

confidence: 76%

Quantum theoretical calculations of van der Waals interactions between molecules. Anisotropic long range interactions

Wormer

Mulder

Avoird

1977

Int J of Quantum Chemistry

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AbstractsPresenting a relatively simple ab initio method to calculate full van der Waals interaction potentials between molecules, we give rules for the optimization of basis functions which permit the reliable evaluation of second order long range interactions. Closed expressions for the long range interaction energy are derived in which the orientational dependence is simplified to the utmost. Calculations show that even for molecules which have no dipole moment, such as ethylene, the strongly anisotropic electrostatic interactions are of the same magnitude as the dispersion interactions, but also that the anisotropic ("cross") terms in the dispersion energy are about equal in size to the corresponding "quadratic" terms. Even though these anisotropic forces cancel to a large extent in the cohesion energy of the ethylene crystal, they can have important effects on some of the other crystal properties.Nous présentons une méthode ah initio relativement simple pour calculer des potentiels complets représentant l'interaction de type van der Waals entre des molécules, et nous donnons des règles pour l'optimisation des fonctions de base, qui permettent une évaluation correcte des interactions à longue portée du second ordre. On obtient des expressions analytiques finies pour l'énergie d 'interaction à longue portée, dans lesquelles la dépendance orientationnelle est simplifiée jusqu'à l'extrême. Des calculs montrent, que même pour des molécules comme l'éthylène, qui n'ont pas de moment dipolaire, les interactions électrostatiques fortement anisotropes sont du même ordre de grandeur que les interactions de dispersion, mais aussi que les termes anisotropes de l'énergie de dispersion ("cross terms") sont presqu'égaux aux termes "carrés" correspondants. Même si ces forces anisotropes se compensent en grand dans l'énergie de cohésion du cristal d 'éthylène, elles peuvent avoir des effects importants sur d'autres propriétés cristallines.

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Section: Introductionsupporting

confidence: 76%

Quantum theoretical calculations of van der Waals interactions between molecules. Anisotropic long range interactions

Wormer

Mulder

Avoird

1977

Int J of Quantum Chemistry

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“…[16][17][18][19][20] The most recent potential has not been tested against thermodynamic and transport property data, 21 such as the quantum second virial coefficients. In the present work, a study of this recent potential was conducted using second virial coefficient data at low temperature.The quantum virial coefficient can be determined by evaluating the quantum ideal gas term, the scattering phase shift dependence on angular momentum [22][23][24][25][26][27][28][29] and the bound states by Levinson's theorem. [25][26] This low-temperature second virial coefficient calculation is an important step to test the quality of the potential under consideration.…”

Section: Introductionmentioning

confidence: 99%

Quantum second virial coefficient calculation for the 4He dimer on a recent potential

Costa¹,

Lemes²,

Alves³

et al. 2013

J. Braz. Chem. Soc.

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Este trabalho concentra-se no cálculo do segundo coeficiente virial quântico, a partir de um potencial desenvolvido recentemente. Este coeficiente foi determinado com 4-5 algarismos significativos na faixa de temperatura de 3 a 100 K. Nossos resultados estão dentro do erro experimental. Três contribuições para o valor total deste coeficiente são o espalhamento quântico (contribuição de estados no contínuo), o estado ligado (contribuição de estados discretos) e o gás ideal quântico; discutimos estas contribuições separadamente. A contribuição mais importante é do espalhamento quântico, enquanto que as contribuições menores são dos estados discretos. Uma análise da sensibilidade foi realizada em função da temperatura para um parâmetro na região de curto alcance do potencial e para três parâmetros na região de longo alcance do potencial. Para ambas as temperaturas consideradas, 10 e 100 K, o coeficiente de dispersão C 6 foi o mais significativo, e o termo dispersão C 10 foi o menos significativo para o resultado total. Em geral, a precisão exigida para descrever os potenciais diminui com o aumento da temperatura. A precisão total e a relação dos parâmetros com os erros experimentais são discutidas. This paper focuses on the calculation of the quantum second virial coefficient, under a recently developed potential. This coefficient was determined to within 4-5 significant figures in the temperature range from 3 to 100 K. Our results are within experimental error. The three contributions to the overall value of the coefficient are the quantum scattering (continuum state contribution), the bound state (discrete state contribution) and the quantum ideal gas; we discuss these contributions separately. The most significant contribution is from the scattering states, whereas the smaller contributions are from the discrete states. A sensitivity analysis was performed as a function of temperature for one parameter in the short-range region of the potential and for three parameters in the long-range regions of the potential. For both temperatures considered, 10 and 100 K, the C 6 dispersion coefficient was the most significant, and the C 10 dispersion term was the least significant to the overall result. In general, the precision required to describe the potential decays as the temperature increases. The overall accuracy and the relationship of the parameters to the experimental errors are discussed.

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“…. a Experimental values taken from the work of Burgmans et al [26]. Dispersion energies calculated according to the formula given in text.…”

Section: Resultsmentioning

confidence: 99%

Investigation of intermolecular interactions based on the atomic statistical model

Radzio‐Andzelm

1981

Int J of Quantum Chemistry

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Possibilities of improving individual contributions to the statistical interaction energy (kinetic and exchange) are examined. A new method of calculating statistical interaction energies is proposed. The exchange term is calculated using a suitably modified second-order gradient correction. For the kinetic contribution the accurate formula corresponding to the first-order perturbation theory is applied. The calculations have been carried out for several pairs of noble gas atoms.

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Attractive well of He–He from 3He–4He differential elastic scattering measurements

Cited by 102 publications

References 31 publications

Quantum theoretical calculations of van der Waals interactions between molecules. Anisotropic long range interactions

Quantum theoretical calculations of van der Waals interactions between molecules. Anisotropic long range interactions

Quantum second virial coefficient calculation for the 4He dimer on a recent potential

Investigation of intermolecular interactions based on the atomic statistical model

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